Effects of Low-Level Laser Therapy Applied Before Treadmill Training on Recovery of Injured Skeletal Muscle in Wistar Rats.
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OBJECTIVE: The aim of this study was to analyze the effects of low-level laser therapy (LLLT) when associated with treadmill training on the recovery of skeletal muscle, during two periods of rest after muscle injury in rats. BACKGROUND DATA: Because of photostimulation, LLLT has been presented as an alternative for accelerating the tissue healing process. MATERIALS AND METHODS: Forty rats were divided into two groups (A and B) containing four subgroups each: GC (Control Group)-cryolesion untreated; EG (Exercise Group)-cryolesion treated with physical exercise; LG (Laser Group)-cryolesion treated with laser; ELG (Exercise and Laser Group)-cryolesion treated with laser and physical exercise. The right tibialis anterior (TA) of the middle belly was injured by a cooling iron bar (cryoinjury). Group A remained at rest for 3 days, whereas Group B remained at rest for 7 days. The laser parameters utilized were 780nm with 15mW average optical power and spot size of 0.04 cm(2) applied during 10sec, leading to 0.152J and 3.8J/cm(2). Treadmill training with and without laser application was performed during 5 days, with each session lasting for 12min at a velocity of 17m/min. Subsequently, the TA muscle was removed for a histological and morphometric analysis. RESULTS: The damaged area was significantly smaller for the ELG at both periods of rest, 3 and 7 days, respectively (4.40.42% and 3.50.14%, p<0.05), when compared with the LG (18.60.64% and 7.50.13%), the EG (210.26% and 8.70.32%), and the CG (23.90.37% and 21.40.38%). In addition, the number of blood vessels were significantly higher for the ELG at both periods of rest, 3 and 7 days, respectively (71.213.51 and 104.511.78, p<0.05), when compared with the LG (60.611.25 and 93.516.87), the EG (51.67.3 and 93.815.1) and the CG (34.42.54 and 65.714.1). CONCLUSIONS: The LLLT applied before the physical exercise on the treadmill stimulated the angiogenesis and accelerated the process of muscle recovery.
